The invention relates to a profiled rail, especially a railway rail, having a reduced total radiated noise level when in use, and comprising a foot section with a bottom surface, a web section, and a head section with a tread surface, and having a rail height and preferably also a rail head width, and in particular a moment of inertia and a section modulus about the axis of the center of gravity, corresponding substantially to those of standard, normally profiled rails having the same load-bearing capacity.
Running rails are profiled, rolled steel bars which are used to build trackways, especially railroad tracks, on which loads can be economically transported. On these tracks, metallic wheels, made preferably from steel or having a steel tire, run on the tread surface of a section of the rail referred to as the rail head. The foot of the rail, which is located opposite to and joined to the head by means of a web, is connected with its bottom surface to a base structure.
In the course of development of railway systems, functionally optimized cross-sectional profiles of rails were appropriately standardized for various loads and applications. In Europe, a frequently used standard profile for railroad rails bears the designation UIC 60; the rail weighs approx. 60 kg/m and tight dimensional tolerances of, for example, .+-.0.6 mm for the rail height and .+-.0.5 mm for the width of the rail head are specified. Tight tolerances in the rail profile are important, especially for the purpose of building a geometrically accurate track intended to permit the speed of trains to be increased without any loss in ride comfort and without any major dynamic loads occurring. In order to reduce wear, rails having heads exhibiting increased hardness are already being manufactured and used.
Despite the highest possible dimensional accuracy, a tread or running surface of the best quality, and smoothness of the rails, as railway cars travel along the track, vibrations, and thus radiated noise, occur. This airborne noise can attain high intensity, especially at high transportation speeds, and it can cause considerable environmental pollution. It has been found that the travel noise generated by trains is caused to a considerable extent by airborne noise radiated from the surface of the rail.
Attempts have already been made by sound-insulating surface sections of the rail to reduce the intensity of the radiated noise.
Applying a coating of vibration-damping material, as proposed in DE-A-4225581 or AT-AS 652/90, is only partially successful in achieving this goal; it is also expensive, prevents visual inspection of the rail in the track and, especially if reinforced polymers are used, it can itself be a source of environmental pollution. In addition, there have been several proposals, e.g. in DE-OS 4411833, to use elastic components in the fastening elements to reduce the transmission of vibrations to the base structure and thus to reduce the amount of airborne noise radiated from this source.
All the devices and arrangements so far proposed to reduce the airborne noise radiated from rails or track installations have in common the disadvantage that they are not very effective, and/or are very expensive, and are aimed essentially at reducing the transmission of vibrations from the rail.